Nasolacrimal duct obstruction (NLDO) is a relatively common clinical problem. Debate continues about optimal management. Intervening early and intervening late each have advantages and disadvantages. We reviewed the world literature on NLDO. We assembled information on occurrence, natural history, and results of treatment. Spontaneous remission data were used to derive the probability of continued obstruction versus age. The prevalence a hypothesized treatment-resistant form of NLDO was estimated. Symptomatic NLDO probably occurs in 5 to 6% of infants. Given a symptomatic case under the age of 14 months, the probability of spontaneous remission within the following month appears to be approximately one of three. Probe failure risk increases with age, doubling every 6 months. Increasing probe failure risk may be due to self-selection. Preliminary analysis of management strategies suggests that lacrimal duct probing at age 4 months in the office is the most cost-effective strategy. Further descriptive studies of NLDO remission and treatment are indicated.